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Top 7 Kombucha Benefits Reviewed (True or Not?)

Researched and Written by:
Richelle Godwin, RDN Richelle Godwin, RDN Jenna Swift, APD Dietitian Jenna Swift, APD Dietitian

If you’ve spent some time Googling around to find out the health benefits of kombucha, you may be under the impression that it is in fact the elixir of life! So in this article, I’m going to walk you through the top 7 most popular health claims about kombucha. For each potential benefit we'll analyze all the evidence…or lack thereof…to figure out which benefits are actually true and which are not. That means by the end of this article, you’ll finally be able to see how drinking kombucha may benefit you and you’ll be able to decide for yourself whether it is worth your time and money.

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    You might have read that it can help boost metabolism and in turn help with weight loss.

    Or perhaps you’ve been told that 1 bottle a day can keep all your gut health issues away.

    And if you’ve really been down the kombucha rabbit hole, maybe you’ve even stumbled upon crazy stories like how President Reagan apparently drank kombucha daily to help him fight off colon cancer!

    Now, ignoring for a minute that Reagan might have been a secret hackysack-kicking hipster at heart, the big question is what health claims are true and what are not?

    Health Claim #1: Kombucha Improves Gut Health

    Kombucha sales are expected to hit $5 billion this year…and arguably the number one reason so many people are buying it, is due to the supposed gut health benefits.

    In fact, if you look at the labels of popular selling kombuchas you’ll see words like rebalance, rebuild and reclaim plastered all over them.  And of course, you’ll see the number one buzzword in gut health “probiotics” there as well. 

    Understandably, when you see this, you can be forgiven for thinking you're drinking a gut health tonic of the gods!  

    And that with regular consumption, you’ll build a bulletproof gut in no time.  But is this actually true?

    Well, here’s what we know from analyzing the top selling kombucha brands…

    Yes, they DO have probiotics in them.  And probiotics in case you don’t know…are beneficial bacteria or yeast that can confer some benefit on your gut health when consumed in adequate amounts.  

    So first impressions would suggest kombucha can indeed support our gut health. 

    Of course, how exactly it does this would depend on the specific probiotics present in the kombucha you’re drinking.

    But guess what - that’s not the full story.  You see, it turns out the probiotic superheroes that kombucha companies mention on their labels and in their marketing, are actually added to their drinks after the tea has already been fermented.

    In other words, the benefits they so talk about are actually thanks to the probiotic supplements they add into their kombucha afterwards.

    If you want to find out why they do this, because it is actually quite a complicated issue and involves regulations around probiotic labeling laws, we go into this in great detail in our article on GTs Kombucha. 

    So given all of this, I guess you’re probably wondering - hang on, are there any actual probiotics naturally present in kombucha that can help my gut health?

    In other words, are there any probiotics that are created due to the natural fermentation process, as opposed to being added into the kombucha after it’s been brewed?

    Well, the answer is maybe.  You see, most kombuchas will naturally contain several species of acetic-acid bacteria and lactic-acid bacteria, as well as friendly yeasts.  And they may have probiotic effects.

    But the reality is that, in order to be technically classified as a quote unquote “probiotic”, these strains need to have been studied and shown to confer a real benefit to humans.

    And right now, we simply don't have those studies.

    Also, the other problem is that the microbial composition of kombucha can vary so much, depending on the SCOBY used, the tea and sugar chosen, the fermentation time, the environment it’s made in and so forth.

    So to wrap this up - kombucha naturally has friendly bacteria and yeast, but we don’t know for sure HOW beneficial they are for gut health.  

    Meanwhile, commercial kombucha definitely does contain probiotics, which can support gut health.  But just remember these are no different to the types of probiotics you’ll find in a probiotic supplement.  

    Important note on kombucha benefits

    Now just before we go on to look at all the other potential health benefits of kombucha, I think it’s interesting to preface it all by saying a few things.
    For starters, many of these benefits are likely due to the tea itself (such as the polyphenols in tea) or the acid components of kombucha, such as acetic acid, lactic acid and DSL acid, among others. 

    With that said, the kombucha fermentation process seems to increase the strength of the benefits found in tea. For example, it increases the total polyphenol count.  And it is of course, only thanks to the fermentation process that we get the beneficial acids.

    The other big thing to highlight, is that pretty much all of the research we’ll talk about in the rest of this article was either done “IN VITRO” or in animals, as opposed to controlled studies of humans. 

    And boy have there been a lot of animal studies.  From rats to rabbits to ducks, and even cattle, scientists have been feeding kombucha to a huge range of animals.  

    And all of this is to say when we come across any encouraging results in the rest of this article, we just need to remember, they merely show that there is some potential for the health claim being true in humans.

    Oh and one other important point for you to keep in mind is that no two kombuchas are created equal.   

    So when you hear about kombuchas in these studies, just bear in mind it may not be the same as the type of kombucha you can buy or make at home.

    Health Claim #2: Kills Harmful Bacteria & Viruses

    The idea that something inside kombucha can hunt down and kill bad bacteria, yeasts and viruses like some sort of mini Jason Bourne, is interesting.  But is it true or not?

    Well, there is research that suggests kombucha MAY be able to do this.
    Specifically when it comes to several food-borne infections such as H. pylori, E. Coli, Salmonella and others.  And even potentially candida yeasts.

    In terms of how it might do this, researchers believe it may be due to the polyphenols and acetic acid in kombucha.  

    And in case you don’t know, acetic acid is the same compound that’s abundant in vinegar.  But until more research is done, the jury is out.

    Health Claim #3: Kombucha Prevents Cancer

    Whenever our research team and I read about the potential anticancer properties of a food or drink, we have to wade through the research slowly and apply extra caution.  

    After all, it is a big claim for people to be making!  So let’s see whether this claim is true or not.

    So first of all, what we do know is that kombucha is made from tea leaves.  And tea leaves are a rich source of polyphenols, a type of antioxidant

    We also know that the longer you ferment kombucha, generally the higher the total polyphenol count.

    Now, according to the journal, Nutrients, a diet rich in natural polyphenols could lower the risk of certain cancers.  In fact, they found “the vast majority of laboratory studies supported anticancer activities of natural polyphenols”.

    But if you dig into the details a bit more, you will also find that there is a lack of clinical trials supporting these lab studies.  

    Of course, we did a bit more digging to see if there were any studies specifically focused on the tea polyphenols in kombucha and their proposed anticancer properties.

    In one study our research team came across, kombucha prepared from green, oolong and black tea was shown to reduce the level of toxicity in human colorectal cancer cells.

    And in another study, kombucha significantly decreased the survival rate of prostate cancer cells.

    But the catch with both of these studies is that they were “in vitro” and conducted on cells - meaning done outside of a living organism.  Which as we know, is not the same as doing studies on actual human beings.  

    So once again, until further studies are done, the health claim that kombucha can prevent or cure cancer is indeed a stretch.

    Health Claim #4: Kombucha Prevents Liver Damage

    The idea that kombucha can help the detoxification process and in turn prevent damage to the liver, is another intriguing health claim.  So is there any merit to this?

    Well, our research team did find some supporting evidence. 

    In studies conducted on liver-damaged mice, researchers found that when the mice were fed kombucha, the rodents experienced less liver cell death. Which really surprised us given that kombucha also does contain some small levels of alcohol.

    And if you want to geek out with me for a second and look at why researchers believed this was happening.  Well, it was reasoned from these studies that kombucha has the ability to protect liver cells by influencing metabolism of fats and reducing the formation of scar tissue in the liver.    

    So yes…kombucha may help with detoxification and protection of the liver… least in mice.

    Health Claim #5: Kombucha Lowers Cholesterol & Heart Disease Risk

    If you’ve been dealt a bad genetic hand or otherwise have a history of high cholesterol, the idea that kombucha can help support healthy cholesterol levels and thus reduce heart disease risk is fascinating.

    But once again, is it true? 

    Well, my research team and I found one study that showed an experiment group were fed a high-cholesterol diet, and then given kombucha extract. 

    Remarkably, unlike the control group, their cholesterol lowered.  Fantastic news, right?  Well the catch is that this study was conducted on a small number of rabbits.

    Meanwhile, other animal studies have shown that kombucha consumption raises levels of HDL or “good” cholesterol, and lowers levels of LDL cholesterol. 

    However, until there are studies on humans proving kombucha lowers cholesterol levels, we can’t come to any firm conclusion on this health claim.

    Health Claim #6: Kombucha Lowers Blood Sugar Levels

    If you look at the label of most popular commercial kombucha brands such as GTs and Kevita, you’ll see they contain on average 10g of sugar per 12 fluid ounces or 355 mils. 

    Now, while that’s a whole lot better than your typical soda, which comes in around the 30g mark.  It begs the question - how can kombucha…a drink with sugar…lower blood sugar levels?

    Well, surprisingly, there is some research that shows that kombucha DELAYS the digestion of carbohydrates, and in turn can help lower blood sugar levels. 

    However, these findings come from animal studies…in this particular case they were focused on poor little diabetic rats. 

    So like with many of the health claims for kombucha…there is some hope here, but further research is needed, specifically in humans.

    Health Claim #7: Kombucha Boosts Metabolism & Weight Loss

    And now onto the final health claim we’ll be looking at…can kombucha speed up your metabolism and help you lose weight? 

    Well, from our research we found no convincing evidence that drinking kombucha aids in weight management or a faster metabolism…well at least not any more than simply drinking the green tea it’s made from. 

    In other words, any potential weight management benefits of kombucha…stem simply from the fact it is made from green tea.

    You see, green tea contains an antioxidant compound called EGCG. And from the limited research we’ve seen, suggests that EGCG may have a beneficial effect on glucose control and weight management.   

    But don’t take this to mean that you can replace daily exercise with a glass of kombucha, especially given most kombucha contains some sugar and thus calories. 

    So to sum up here, the evidence seems to be weak.

    Health risks of kombucha

    Just before we wrap things up it’s important to know that kombucha is not without its potential downsides.  And there can indeed be some risks to consuming kombucha on the regular.  But the funny thing is that like with the health benefit claims, many of the risks talked about online are also overblown.  

    So once again, if you want to sort fact from fiction, check out our other article on the health risks of kombucha.

    Our conclusion

    As we’ve seen there are a lot of different health claims being thrown around by kombucha companies and lovers alike.  But the reality is that most of them need more research.  And in particular, they need controlled studies involving humans.

    In the meantime though, we can be cautiously optimistic that kombucha is good for our health.

    You see, although we’re not sure about its natural probiotic benefits, it does deliver lots of other benefits thanks to the green tea itself…hello antioxidant-rich polyphenols…and these benefits are heightened due to the fermentation process.  Meaning kombucha is more beneficial than the tea by itself.  

    And additionally, the fermentation process also create acids such as acetic acid and lactic acid, which may offer other health benefits.

    Perhaps best of all, kombucha is playing a massive role in reducing soda consumption, and thus sugar consumption.  And if you find yourself swapping your Coca Cola for a glass of kombucha - well then for us, that’s more than reason enough to enjoy this fizzy fermented tea!

    Compare fermented foods

    Now I’m sure you’re wondering how does kombucha compare to other fermented foods like kefir, kimchi and sauerkraut.  Specifically, which are the healthiest fermented foods for you?  

    Well, to find the answers you’re looking for, my research team and I have created a free Fermented Foods Comparison tool.  In it, you’ll find all the answers you’re looking for, including which foods have the most probiotics, nutrients and even how to make them. 

    Evidence Based

    An evidence hierarchy is followed to ensure conclusions are formed off of the most up-to-date and well-designed studies available. We aim to reference studies conducted within the past five years when possible.

    • Systematic review or meta-analysis of randomized controlled trials
    • Randomized controlled trials
    • Controlled trials without randomization
    • Case-control (retrospective) and cohort (prospective) studies
    • A systematic review of descriptive, qualitative, or mixed-method studies
    • A single descriptive, qualitative, or mixed-method study
    • Studies without controls, case reports, and case series
    • Animal research
    • In vitro research

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